Priapism is painful, persistent, abnormal erection unaccompanied by sexual desire or excitation. It is most common in boys aged 5 to 10 years and in men aged 20 to 50 years.
Pathophysiology of Priapism
The penis is composed of 3 corporeal bodies: 2 corpora cavernosa and 1 corpus spongiosum. Erection is the result of smooth muscle relaxation and increased arterial flow into the corpora cavernosa, causing engorgement and rigidity.
Ischemic priapism
Most cases of priapism involve failure of detumescence and are most commonly due to failure of venous outflow (ie, low flow), also known as ischemic priapism. Severe pain from ischemia occurs after 4 hours. If prolonged > 4 hours, priapism can lead to corporeal fibrosis and subsequent erectile dysfunction or even penile necrosis and gangrene.
Stuttering priapism is a recurrent form of ischemic priapism with repeated episodes and intervening periods of detumescence.
Nonischemic priapism
Less commonly, priapism is due to unregulated arterial inflow (ie, high flow), usually as a result of formation of an arterial fistula after trauma. Nonischemic priapism is not painful and does not lead to necrosis. Subsequent erectile dysfunction is common.
Etiology of Priapism
In adults, the most common cause (see table Some Causes of Priapism) is
Medications for erectile dysfunction
In children, the most common causes are
Hematologic disorders (eg, sickle cell disease, less commonly leukemia)
In many cases, priapism may be idiopathic and recurrent.
Some Causes of Priapism
Cause | Suggestive Findings | Diagnostic Approach |
|---|---|---|
Medications for erectile dysfunction: | Painful ischemic priapism in men with history of treatment for erectile dysfunction | Clinical evaluation |
Illicit drugs: | Painful ischemic priapism and psychomotor agitation and anxiety | Clinical evaluation Sometimes toxicology screen |
Other medications:
| Painful ischemic priapism in men undergoing treatment for another medical disorder | Clinical evaluation |
Hematologic disorders:
| Young males, often of African or Mediterranean descent | Complete blood count Hemoglobin electrophoresis |
Locally advanced prostate cancer Any metastatic disease | Men > 50 with history of increasing symptoms of bladder outlet obstruction | Prostate-specific antigen testing CT |
Spinal cord stenosis or compression Continuous epidural infusions | Concomitant lower-extremity weakness | CT or MRI of the spine |
Trauma (resulting in unregulated arterial inflow or arterial fistula formation) | Nonischemic, nonpainful priapism in men with recent trauma | Penile duplex ultrasonography Angiography MRI |
Rare causes:
| Various | Various |
* All atypical antipsychotics may cause priapism. | ||
Evaluation of Priapism
Priapism requires urgent treatment to prevent chronic complications (primarily erectile dysfunction). Evaluation and treatment should be done simultaneously.
History
History of present illness should cover the duration of erection, presence of partial or complete rigidity, presence or absence of pain, and any recent or past genital trauma. The medication history should be reviewed for offending medications, and patients should be directly asked about the use of illicit drugs and medications used to treat erectile dysfunction.
Review of systems should seek symptoms suggesting a cause, including dysuria (urinary tract infections), urinary hesitancy or frequency (prostate cancer), fever and night sweats (leukemia), and lower-extremity weakness (spinal cord pathology).
Past medical history should identify known conditions associated with priapism (see table Some Causes of Priapism), particularly hematologic disorders. Patients should be asked about a family history of hemoglobinopathies (sickle cell disease or thalassemia).
Physical examination
A focused genital examination should be done to evaluate extent of rigidity and tenderness and determine whether the glans and corpus spongiosum are also affected. Penile or perineal trauma and signs of infection, inflammation, or gangrenous change should be noted.
The general examination should note any psychomotor agitation, and the head and neck examination should look for pupillary dilation associated with stimulant use. The abdomen and suprapubic area should be palpated to detect any masses or splenomegaly, and a digital rectal examination should be done to detect prostatic enlargement or other pathology. Neurologic examination is useful to detect any signs of lower-extremity weakness or saddle paresthesias that might indicate spinal pathology.
Red flags
The following findings are of particular concern:
Pain
Priapism in a child
Recent trauma
Fever and night sweats
Perineal and/or lower extremity neurologic manifestations
Interpretation of findings
In most cases, the clinical history reveals a history of medication treatment for erectile dysfunction, illicit drug use, or a history of sickle cell disease or trait; in these cases, no testing is indicated.
In patients with ischemic priapism, physical examination typically reveals complete rigidity with pain and tenderness of the corpus cavernosa and sparing of the glans and corpus spongiosum. By contrast, nonischemic priapism is painless and nontender, and the penis may be partially or completely rigid.
Testing
If the cause is not obvious, screening is done for hemoglobinopathies, leukemia, lymphoma, urinary tract infection, and other causes:
Complete blood count
Urinalysis and culture
Hemoglobin electrophoresis in Black people and men of Mediterranean descent
Many clinicians also do drug screening, intracavernosal arterial blood gas testing, and duplex ultrasonography. Penile duplex ultrasonography will show little or absent cavernosal blood flow in men with ischemic priapism and normal to high cavernosal blood flow in men with nonischemic priapism. Ultrasonography may also reveal anatomic abnormalities, such as cavernous arterial fistula or pseudoaneurysm, which usually indicate nonischemic priapism. Occasionally, MRI with contrast is useful to demonstrate arteriovenous fistulas or aneurysms.
Treatment of Priapism
Treatment is often difficult and sometimes unsuccessful, even when the etiology is known. Whenever possible, patients should be referred to an emergency department; patients should preferably be seen and treated urgently by a urologist. Other disorders should be treated. For example, priapism often resolves when sickle cell crisis is treated. Measures used to treat priapism itself depend on the type.
Ischemic priapism
If these measures are unsuccessful or if priapism has lasted > 48 hours (and is thus unlikely to resolve with these measures), a surgical shunt can be created between the corpus cavernosum and glans penis or corpus spongiosum and another vein.
Stuttering priapism
Stuttering priapism, when acute, is treated in the same way as other forms of ischemic priapism. There is a report of several cases caused by sickle cell diseaseestrogentestosterone level to <
Nonischemic priapism
Conservative therapy (eg, ice packs and analgesics) is usually successful; if not, selective embolization or surgery is indicated.
Refractory priapism
If other treatments are ineffective, a penile prosthesis can be placed.
Key Points
Priapism requires urgent evaluation and treatment.
Medications, substances, and sickle cell disease are the most common causes.
Acute treatment is with alpha agonists, needle decompression, or both.
